JPH0460037B2 - - Google Patents

Description

[Detailed description of the invention] <Field of application of the invention> The present invention relates to recording materials.

The recording material according to the present invention utilizes a color-forming reaction between an electron-donating colorless dye and an electron-accepting compound, and particularly relates to a recording material using a novel electron-accepting compound.

The electron-accepting compound according to the present invention is particularly useful as an electron-accepting compound for pressure-sensitive recording materials and heat-sensitive recording materials. This compound can also be applied to electron beam recording sheets, electrostatic recording sheets, photosensitive pressure-sensitive recording sheets, etc.

<Prior art> The use of various phenol compounds as electron-accepting compounds in pressure-sensitive recording materials or heat-sensitive recording materials is disclosed in Japanese Patent Publication No. 40-9309, Japanese Patent Publication No. 45-14039,
Although disclosed in Japanese Patent Publication No. 51-29830, etc., these phenol compounds cannot necessarily be said to be satisfactory electron-accepting compounds. That is, (1) the coloring density is not sufficient when used in combination with an electron-donating colorless dye. (2) When 2,4-dihydroxybenzoic acid ester is used in a heat-sensitive recording material, the moisture and heat resistance of the recording material is insufficient, and fogging is likely to occur. (3) After recording, the density of the image area decreases over time. There were many problems that needed to be improved, such as the occurrence of white powdery matter, which is called powdering, and the concentration of white powder on the surface.

The present inventors have been developing 2,4-dihydroxy-6-substituted benzoic acid esters.
However, by focusing on the ester moiety in particular, we have proceeded with improvements, and have found that a compound with a specific skeleton has an effect that is at least as good as that of the invention that has already been filed, resulting in the creation of the present invention.

<Object of the Invention> Therefore, the object of the present invention is to provide a recording material which has sufficient color density when used in combination with an electron-donating colorless dye and which has improved storage stability both raw and over time.

<Structure of the Invention> A recording material using the present invention, an electron-donating colorless dye, and an electron-accepting compound, characterized in that the electron-accepting compound is a compound represented by the following general formula.

In the above formula, R ₁ is a methyl group or a carbon atom number of 1 to
8 alkoxy group, R ₂ has 1 to 5 carbon atoms
represents alkylene, alkenylene or oxaalkylene, and Ar represents a benzene ring or naphthalene ring.

When the electron-accepting compound according to the present invention is used as an electron-accepting compound for heat-sensitive recording materials, the temperature is 50°C.
It is preferable to have a melting point of 70℃ or higher, especially 70℃~
Those having a melting point of 150°C are preferred.

The characteristics of the electron-accepting compound according to the present invention include the following.

(i) When combined with an electron-donating colorless dye, it provides a highly concentrated colored image.

(ii) Poor water solubility.

(iii) Stable without sublimation.

(vi) It is easy to synthesize and can be obtained in high yield and purity. The raw materials are also cheap.

Regarding the simplicity of synthesis, for example, compounds in which R ₁ is a methyl group, R ₂ Ar is a benzyl group, a phenethyl group, a phenoxyethyl group, or a cinnamyl group can be synthesized using 2 moles of diketene and benzyl alcohol, phenethyl alcohol, or cinnamyl group as raw materials. A simple and low-cost synthesis method using an alcohol such as enoxyethanol or cinnamyl alcohol and a small amount of base can be applied.

Although it is not yet clear what causes the above-mentioned effects of the electron-accepting compound of the present invention, it is thought to be as follows.

In recording systems that utilize contact between an electron-accepting compound and an electron-donating compound, ester-based compounds usually exhibit a desensitizing effect, which poses a problem in storage stability after recording. However, as can be seen from the above formula, the electron-accepting compound of the present invention is substituted at both the 2- and 6-positions adjacent to the ester moiety, and one of them is a hydroxy group, so it has a 6-membered ring. I think this is due to the fact that it is easy to form hydrogen bonds, the electron pairs in the ester part are fixed, making it difficult to have other negative effects, and furthermore, the ester bond is wrapped in a bulky substituent called R ₂ Ar. It will be done.

Next, specific examples of the electron-accepting compound of the present invention will be shown, but the present invention is not limited thereto.

(1) 2,4-dihydroxy-6-methylbenzoic acid benzyl ester (2) 2,4-dihydroxy-6-methoxybenzoic acid p-methylbenzyl ester (3) 2,4-dihydroxy-6-methylbenzoic acid cinnamon Mill ester (4) 2,4-dihydroxy-6-methylbenzoic acid p-methoxyphenethyl ester (5) 2,4-dihydroxy-6-methylbenzoic acid p-isopropylbenzyl ester (6) 2,4-dihydroxy- 6-Methylbenzoic acid p-benzyloxyphenoxyethyl ester (7) 2,4-dihydroxy-6-methylbenzoic acid p-methylphenoxyethyl ester and the like.

These may be used alone or in combination, or mixed with other substances such as bisphenol A, benzyl 4-hydroxybenzoate, phenethyl 2,4-dihydroxybenzoate, and 1,1-bis-4-hydroxyphenylcyclohexane. used. When mixing, the ratio is determined in consideration of solubility, temperature at which color development starts, solvent resistance, etc. In particular, zinc salts of salicylic acid derivatives and the like are used in combination to provide favorable light resistance and finger squeeze resistance.

As the electron-donating colorless dye used in the present invention, triarylmethane compounds, diphenylmethane compounds, xanthene compounds, thiazine compounds, spiropyran compounds, etc. are used. To illustrate some of these, triarylmethane compounds include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3,3-bis(p-dimethylaminophenyl) Phthalide, 3-(p-dimethylaminophenyl)-3-(1,3-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-methylindole-3- Diphenylmethane compounds include 4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leucoauramine, and N-2,4,5-trichlorophenylleucoauramine. Examples of xanthene compounds include rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine B (p-chloroanilino)lactam, 2-dibenzylamino-6-diethylaminofluorane, and 2-anilinolactam. -6-diethylaminofluorane, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-N-cyclohexyl-N-methylaminofluorane, 2-anilino-3-methyl- 6-
N-ethyl-N-isoamylaminofluorane,
2-o-chloroanilino-6-diethylaminofluorane, 2-(3,4-dichloroanilino)-6
-diethylaminofluorane, 2-octylamino-6-diethylaminofluorane, 2-anilino-3-methyl-6-diphenylaminofluorane, 2-anilino-3-methyl-5-chloro-6
-diethylaminofluorane, 2-anilino-3
-Methyl-6-diethylamino-7-methylfluorane, 2-butylamino-3-chloro-6-diethylaminofluorane, 2-ethoxyethylamino-3-chloro-6-diethylaminofluorane, 2-anilino-3- Chloro-6-diethylaminofluorane, 2-anilino-3-methyl-6
-Dioctylaminofluorane, 2-dimethylaminocarbonylethylamino-6-diethylaminofluorane, 2-o-chloroanilino-6-dibutylaminofluorane, 2-anilino-3-pentadecyl-6-diethylaminofluorane, 2
-anilino-3-ethyl-6-dibutylaminofluorane, 2-anilino-3-ethyl-6-N-
Ethyl-N-isoamylaminofluorane, 2-
Anilino-3-methyl-6-N-ethyl-N-γ
-methoxypropylaminofluorane, 2-p-
There are chloroanilino-3-phenyl-6-diethylaminofluoran, 2-phenyl-6-diethylaminofluoran, etc. Thiazine compounds include benzoylleucomethylene blue, p-nitrobenzylleucomethylene blue, etc., and spiro compounds include: 3-Methyl-spiro-sinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-dichloro-spiro-dinaphthopyran, 3-benzylspiro-dinaphthopyran, 3-
Examples include methyl-naphtho(3-methoxy-benzo)-spiropyran and 3-propyl-spiro-dibenzopyran. These may be used alone or in combination.

Next, a specific method for manufacturing the recording material according to the present invention will be described.

The pressure-sensitive copying paper according to the present invention is disclosed in U.S. Patent No. 2505470.
No. 2505471, No. 2505489, No. 2548366,
It can take various forms as described in prior patents such as No. 2712507, No. 2730456, No. 2730457, and No. 3418250. Most commonly, it will consist of at least one pair of sheets separately containing an electron-donating colorless dye and an electron-accepting compound according to the invention. That is, electron-donating colorless dyes, alone or in combination, are dissolved in a solvent (synthetic oil such as alkylated naphthalene, alkylated diphenyl, alkylated diphenylmethane, alkylated diarylethane, chlorinated paraffin, etc.), and this is dispersed in a binder. Alternatively, after containing it in microcapsules, it can be applied to a support to form a coloring agent sheet, and an electron-accepting compound alone or in a mixture or together with other electron-accepting compounds, styrene-butadiene latex, A developer sheet is obtained by dispersing it in a binder such as polyvinyl alcohol and applying it to a support such as paper, plastic sheet, resin coated paper, etc.

The amounts of the electron-donating colorless dye and the electron-accepting compound to be used depend on the desired coating thickness, the form of the pressure-sensitive copying paper, the capsule manufacturing method, and other conditions, and may be appropriately selected depending on the conditions.

U.S. patent for method of manufacturing capsules
A method using coacervation of a hydrophilic colloid sol described in No. 2800457 and No. 2800458,
British Patent No. 867797, British Patent No. 950443, British Patent No. 989264, British Patent No.
Examples include the interfacial polymerization method described in No. 1091076.

The heat-sensitive recording material is prepared by adding an electron-donating colorless dye, an electron-accepting compound according to the present invention, and, if necessary, a thermofusible substance to a liquid in which a binder is dissolved or dispersed, individually or in combination, and sufficiently finely ground. After mixing, oil-absorbing pigments such as kaolin, calcined kaolin, talc, diatomaceous earth, calcium carbonate, aluminum hydroxide, acid clay, barium sulfate, urea-formalin filler, and cellulose filler are added to form a coating solution. If necessary, a paraffin wax emulsion, a latex binder, a sensitivity improver, a metal soap, an antioxidant, an ultraviolet absorber, an image storage improver, etc. can be added.

The coating solution is applied to a support such as neutral paper, high-quality paper, or plastic film and dried. When preparing a coating liquid, all the components may be mixed and pulverized at the same time from the beginning, or they may be combined in appropriate combinations, pulverized and dispersed separately, and then mixed.

The amounts of each component constituting the heat-sensitive recording material are 1 to 2 parts by weight of an electron-donating colorless dye, 1 part by weight of an electron-accepting compound, and 1 part by weight of an electron-donating colorless dye.
~6 parts by weight, 0 to 30 parts by weight of thermofusible substance, 0 pigments
It generally consists of ~15 parts by weight, 1 to 15 parts by weight of binder, and small amounts of antioxidants, fluorescent brighteners, dispersants, etc.

One or more electron-donating colorless dyes may be used in combination.

Examples of binders used in the present invention include styrene-butadiene copolymers, modified acrylamide copolymers, carboxy-modified polyvinyl alcohol, acrylic latex, vinyl acetate copolymers, styrene-maleic anhydride copolymers, and hydroxyethyl cellulose. be able to.

As thermofusible substances, erucic acid,
Stearic acid, behenic acid, palmitic acid, stearamide, behenic acid amide, stearanilide, stearic acid toluidide, N-myristoyl-p-anisidine, N-myristoyl-p-
phenetidine, 1-methoxycarbonyl-4-N
-stearylcarbamoylbenzene, N-octadecylurea, N-hexadecylurea, N,
N'-didodecylurea, phenylcarbamoyloxidedodecane, p-t-butylphenolphenoloxyacetate, p-phenylphenol-p
-chlorophenoxy acetate, 4,4'-isopropylidene bismethoxybenzene, β-phenylethyl-p-phenyl phenyl ether, 2-p
-chlorobenzyloxynaphthalene, 2-benzyloxynaphthalene, 1-benzyloxynaphthalene, 2-phenoxyacetyloxynaphthalene, phthalic acid diphenyl ester, 1-hydroxy-2-naphthoic acid xylyl ester, 2-benzoyloxynaphthalene, p-benzyloxybenzoic acid benzyl ester, hydroquinone acetate hydroxynaphthoic acid phenyl, p-methoxycarbonylbenzoic acid butyramide, etc. are used.

These substances are colorless solids at room temperature;
It is a substance that has a sharp melting point at a temperature suitable for copying heating temperatures, that is, around 70 to 130°C.

Examples of waxes include paraffin wax, carnauba wax, microcrystalline wax, polyethylene wax, and higher fatty acid amides such as stearic acid amide, ethylene bisstearamide, and higher fatty acid esters.

Examples of metal soaps include higher fatty acid polyvalent metal salts such as zinc stearate, aluminum stearate, calcium stearate, and zinc oleate.

As the image preservation improving agent, phenols or derivatives thereof in which at least one of the 2nd and 6th positions is substituted with an alkyl group, preferably a branched alkyl group, are preferred. Further, those having a plurality of phenol groups in the molecule are preferred, and those having 2 to 3 phenol groups are particularly preferred. Specific examples of these compounds include: bis[3,3-bis-(2'-methyl-4'-hydroxy-5'-tert-butylphenyl)-butanoic acid] glycol ester, 1,1,3 -tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 4,4'-thiobis(2-methyl-6-tert-
butylphenol), 2,2'-thiobis(4-methyl-6-tert-
butylphenol), 2,2'-methylenebis(4-methyl-6-
tert-butylphenol), 4,4'-butylidene bis(3-methyl-6-
tert-butylphenol), etc.

The amount of these compounds used is 5 to 200 weight percent, preferably 20 percent by weight, based on the electron accepting compound.
~100% by weight.

Examples will be shown below, but the present invention is not limited only to these examples.

Example 1 Preparation of color former sheet 2-anilino-3- which is an electron-donating colorless dye
1 g of a 1:1 mixture of methyl-6-diethylaminofluorane and 2-anilino-3-chloro-6-dibutylaminofluorane was dissolved in 30 g of isopropyl diphenylethane. Add this solution to gelatin 6
g and 4 g of gum arabic dissolved in 50 g of water were added to 50 g of water with stirring to emulsify to form oil droplets with a diameter of 1 μm to 10 μm, and then 250 g of water was added. Add acetic acid and adjust the pH to about 4
Coacervation was induced, a wall of gelatin and gum arabic was created around the oil droplets, formalin was added, and the pH was raised to 9 to harden the wall.

The thus obtained microcapsule dispersion was applied to paper and dried to obtain a color former sheet.

Preparation of color developer sheet 20g of 2,4-dihydroxy-6-methylbenzoic acid benzyl ester, which is an electron-accepting compound, was
% polyvinyl alcohol aqueous solution 200g,
Further, 20 g of kaolin (diyodia kaolin) was added and well dispersed to form a coating liquid. The obtained coating liquid was applied to paper and dried to obtain a color developer sheet.

When the thus prepared color former sheet and color developer sheet were brought into contact with each other and pressure was applied, a black printed image was instantaneously obtained. This image had high density and excellent light resistance and heat resistance.

Example 2 2-anilino-3-, an electron-donating colorless dye
4g of methyl-6-N-methyl-N-cyclohexylaminofluorane, 1g of 2-anilino-3-pentadecyl-6-diethylaminofluorane, 0.01g of Tinuvin p 5% polyvinyl alcohol 1.Polymerization degree 99%, degree of polymerization 1000 ) Processed in a sand mill with 50 g of an aqueous solution to obtain a dispersion with an average particle size of 2 μm.
Similar to this, 2,4-dihydroxy-6-methyl-
10 g of phenethyl benzoate ester and 100 ml of a 5 g polyvinyl alcohol aqueous solution were processed in a sand mill. After mixing these two dispersions, 10 g each of kaolin and synthetic calcium carbonate were added and dispersed well, and a paraffin wax emulsion was prepared.
A coating liquid was prepared by adding 5 g of a 50% dispersion (Chukyo Yushi Cellosol #428).

The coating liquid was applied to neutral paper with a basis weight of 50 g/m ² so that the coating amount was 58 g/m ² , and it was heated at 60°C for 1 hour.
A coated paper was obtained by drying for a minute.

Apply energy to heat coated paper using facsimile
When heated and colored at 40 mJ/mm ² , a black printed image was obtained, and the color density was 1.16. Also, this coated paper
The fog density after being left at 40°C and 90% RH for 24 hours was 0.08. Further, this recording paper did not cause powder blowing even when it was sandwiched between vinyl sheets.

Example 3 5 g of 2-anilino-3-chloro-6-diethylaminofluorane was used as the electron-donating colorless dye in place of the electron-donating colorless dye of Example 2, and 2,4- as the electron-accepting compound. A coated paper was obtained in the same manner as in Example 2, except that 10 g of p-methylphenoxyethyl dihydroxy-6-methylbenzoate was used.

Apply energy to heat coated paper using facsimile
A black impression was obtained when color was developed at 40 mJ/mm ² .
The color density was 1.06.

Comparative Example 1 Coated paper was obtained in the same manner as in Example 3 using 10 g of 2,2-bis-(4-hydroxyphenyl)propane as the electron-accepting compound instead of the electron-accepting compound in Example 3. Ta.

Apply energy to heat coated paper using facsimile
When heated at 40mJ/ ^mm2 , the color density was 0.58.
It was hot.

Comparing Examples 2 and 3 with Comparative Example 1, it is clear that the electron-accepting compound of the present invention has extremely high coloring properties.

Comparative Example 2 A coated paper was obtained in the same manner as in Example 3 except that 10 g of benzyl 2,4-dihydroxybenzoate was used as the electron-accepting compound instead of the electron-accepting compound in Example 3.

Apply energy to heat coated paper using facsimile
When heated at 40mJ/ ^mm2 , the color density was 1.05.
It was hot.

Further, the density of the coated paper after being left at 40° C. and 90% RH for 24 hours was 0.81.

Comparing Example 2 and Comparative Example 2, it is clear that the recording paper using the electron-accepting compound of the present invention has excellent moist heat resistance.

Claims (1)

[Scope of Claims] 1. A recording material using an electron-donating colorless dye and an electron-accepting compound, characterized in that the electron-accepting compound is a compound represented by the following general formula. [In the above formula, R ₁ is a methyl group or a carbon atom number of 1
It represents an alkoxy group having 1 to 8 carbon atoms, R ₂ represents an alkylene, alkenylene or oxaalkylene having 1 to 5 carbon atoms, and Ar represents a benzene ring or a naphthalene ring. ]